ETC ETC Laboratory Analysis & Forensic Science 3

Question 1

What is locard's exchange principle and how does it apply to forensic analysis?

Accepted Answer

Every contact leaves a trace — evidence is transferred between persons and crime scenes during contact

Answer

All evidence must be logged before analysis begins

Answer

Chain of custody requires two witnesses at all times

Answer

Crime scene photographs must precede physical collection

Question 2

Which reagent is used as a presumptive test for blood that produces a luminescent reaction?

Accepted Answer

Luminol

Answer

Phenolphthalein (Kastle-Meyer)

Answer

Leuco Malachite Green

Answer

Hemastix strips

Question 3

What is the role of a forensic laboratory's evidence custodian?

Accepted Answer

To maintain chain of custody records and control access to submitted evidence

Answer

To perform chemical analysis on submitted samples

Answer

To collect evidence directly from crime scenes

Answer

To testify as an expert witness in court

Question 4

Why must forensic analysts wear PPE including gloves and masks when handling evidence?

Accepted Answer

To prevent cross-contamination of the evidence with analyst DNA or materials

Answer

To comply with OSHA fire safety regulations only

Answer

To protect against radioactive evidence exclusively

Answer

To maintain a sterile environment for chemical synthesis

Question 5

Which type of evidence requires refrigeration at 2–8°C upon submission to the forensic laboratory?

Accepted Answer

Biological samples such as blood, saliva, and semen swabs

Answer

Firearms and ammunition

Answer

Questioned documents

Answer

Controlled substance powders

Question 6

What does a 'confirmatory test' in forensic analysis provide that a presumptive test does not?

Accepted Answer

A definitive, scientifically validated identification of the substance

Answer

A rapid field screening result

Answer

A color-change indicator for the presence of a substance

Answer

An approximate concentration estimate